Lumps in the groin

What are the most common causes of lumps in the groin?

Lumps can come from any structure in the groin, at any level from the skin on the outside, to the bone on the inside.

The most common causes of lumps in the groin are:

Skin infections

This includes infections such as boils or abscesses. Sometimes infections can develop around the hair follicles of pubic hair in this area, particularly if there is trauma from shaving or waxing or from rubbing on underwear. These lumps would be red or pink and sore. It hurts to touch them. They can vary from slightly sore pimples to very large abscesses.

Rarely, skin infections are due to an underlying medical condition. Hidradenitis suppurativa is one example. This is a long-term (chronic) skin condition, leading to painful and repeated lumps of pus (boils or abscesses).

Swollen lymph glands

Lymph glands are small lumps all around your body that are part of your immune system. They help you fight infection. Most people can't feel their lymph glands normally (sometimes, they can be felt in very slim people and in children), but if they become swollen you may feel them as a lump or lumps.

The groin is one part of your body where this can occur. The most common cause of swollen lymph glands is infection. This is your lymph glands just doing their job and fighting off the infection. Infections of the areas around the groin may cause the lymph nodes in the groin to swell - for example sexually transmitted infections (STIs), nappy rashes, or skin infections.

Lymph glands can also swell up in response to infections which affect your whole system, such as glandular fever, chickenpox or flu. When lymph glands swell due to infection, they usually settle back to their normal size once the infection has gone.

Less commonly, lymph glands can swell due to a type of cancer. Cancers of the blood system, such as lymphoma or leukaemia, can cause swollen lymph glands. Cancers from other parts of the body can also spread to the lymph nodes, causing them to become bigger. Lymph glands which are swollen due to a type of cancer tend to be hard or solid, and do not go away as they do when swollen due to infection. They usually grow slowly, whereas glands swollen due to infection appear suddenly.

There are some other uncommon causes of swollen lymph nodes, such as sarcoidosis, systemic lupus erythematosus (SLE), HIV and AIDS.

Hernias

A hernia occurs when an internal part of the body pushes through a weakness in the surrounding muscle or tissue wall. The groin is a common site for a hernia, and there are three types of hernia which can occur here. These are all types of bowel hernia, where bowel and other things inside the abdomen push out through a weakness in the abdominal wall. They are:

• An inguinal hernia - more common in males.

• A femoral hernia - more common in females.

• An incisional hernia - in the area of a previous operation scar or injury.

A hernia usually feels very soft and tends to go away when you lie down. If the tissue inside the hernia gets stuck, it can be hard and painful. If this occurs, you should see a doctor urgently.

What do you mean by the groin?

Your groin is the part just above the top of your legs, between the lowest part of your tummy and the top of your thigh. You have a groin on either side, around the crease where your leg joins the rest of your body. The groin is over the hip joint and contains several of the muscles of the leg.

There is a group of glands (lymph nodes) in the groin area, which normally cannot be felt. It also contains the inguinal canal on each side. The inguinal canal is a passageway for structures such as ligaments to pass between the tummy and the genital area.

See also the separate leaflet called Scrotal Lumps/Pain and Swelling.

What are the other possible causes of lumps in the groin?

Other skin lumps

Other than infection, there can be other skin conditions which can cause a lump in the groin. For example:

• Fluid-filled lumps (cysts).

• Warts. These are little skin lumps caused by a virus. Those around the genital area are called genital warts and may be sexually transmitted.

• Tumours of the skin. These can be non-cancerous (such as papillomas) or cancerous. The groin is an uncommon place to get a skin cancer as it is not exposed to the sun as much as other parts of the body usually.

Fatty lumps

Lumps which come from the layer of fat beneath the skin are called lipomas. They are quite common and can occur anywhere in the body where there is a layer of fatty tissue. They feel quite soft and usually are harmless.

Enlarged blood vessels

Sometimes a vein or artery can become swollen, causing a lump. A swollen femoral artery in the groin is called a femoral aneurysm. Swollen veins are called varicose veins, and in the groin this is called a saphena varix.

Undescended testicle

While a baby boy is growing inside his mother's womb, his testicles (testes) gradually move from inside his tummy down to the bag or sac (the scrotum) under his penis. Sometimes one gets stuck along the way, and sometimes can be felt as a small lump in the groin.

Baby boys are checked at birth and at six weeks to be sure their testicles are in the scrotum. If the testicles have not moved down to the scrotum by the age of 6 months they may need an operation to move the testicles to where they should be.

What are the causes of pain in the groin?

Some of the causes of lumps above also cause pain, such as skin infections and (sometimes) hernias.

There are also several things that cause groin pain in this area without any lumps. The most common cause of this is a problem with your hip, in particular wear and tear (osteoarthritis of the hip). Another common cause is a pulled or torn muscle (a groin strain), usually from a sporting injury.

When should I worry about a lump in my groin?

Always see a doctor if you have an unexplained lump which does not settle on its own. See a doctor as soon as possible if your lump seems to be getting bigger. See a doctor urgently if:

• The lump is very painful.

• You have pain in your tummy area along with being sick (vomiting) and/or not being able to poo.

• You have a high temperature (fever) and feel unwell in yourself.

Will I need any tests?

Your doctor will ask you some questions, and then examine the lump or lumps in your groin. Sometimes, this is all that's needed to make a diagnosis. For example, if you have a one-off boil or abscess you generally don't need any more tests.

In other cases, an ultrasound scan will be helpful. This can confirm the type of lump you have, and give more information about it. For example, if your doctor thinks your lump is a hernia, a scan can confirm this and determine which type of hernia it is and whether it needs treatment.

The scan shows what the lump is made out of. For example, if it shows fatty tissue, it suggests a non-cancerous fatty lump (lipoma). If you have an aneurysm, the scan will show a swollen artery. Undescended testicles can be seen on an ultrasound scan. A lump filled with fluid suggests a cyst, and so on.

Blood tests may also be helpful. These can help determine if swollen lymph glands are due to infection, and in some cases blood tests can help find the cause of the infection. In people who get repeated boils or abscesses a blood test to check for an underlying reason such as diabetes may be useful.

Occasionally it may be necessary to take a sample of the lump for further analysis. This is called a biopsy. A sample of the tissue inside the lump can be taken with a thin needle, or the whole lump removed. The sample is then examined under the microscope to find out the cause. This is helpful if some kind of cancerous lump or lymph gland is suspected.

What is the treatment for lumps in the groin?

This is different depending on the cause. There is no one single treatment for all lumps in the groin. Once your doctor finds the cause, he or she will advise on treatment options.